1. Field of the Invention
The present invention relates to a printer and, more particularly, to a printer in which a type wheel, a printing hammer and the like are mounted on a carriage and the type-printing is performed by striking types arranged around the type wheel due to the hitting operation of the printing hammer.
2. Description of the Prior Art
Hitherto, in such a kind of printer, the types arranged around the type wheel are struck toward a printing paper through an ink ribbon by way of the printing hammer. However, the type wheel, printing hammer, wheel driving motor, ink ribbon, etc. are mounted on the carriage, and the type wheel is rotated while it is moved to the next printing position by the carriage. Upon printing operation, the type wheel is held in the still state for the platen which holds the paper. After completion of the printing, the type wheel is again rotated for selection of the next type to be printed and is moved by the carriage.
On one hand, the optimum values of the hitting pressures of the types by the printing hammer differ in dependence on the size of the type areas. Therefore, in general, such a printer is provided with a table of the hitting pressures corresponding to the type areas and is constituted in such a manner that the hitting pressure is controlled so that the optimum hitting pressure is derived for every type by looking up this table. Since the mass of the hammer is constant, to obtain such an optimum hitting pressure, a current or the like is applied to a magnet coil in order to change the speed of the hammer to control the hitting force with which the hammer strikes the wheel.
However, in such a conventional printer, in the foregoing series of printing operations, a rotation start signal to rotate the type wheel and a movement start signal to move the carriage are output after the expiration of a constant still time, after upon completion of single printing operation. Thus, it is necessary to reduce the still time of the carriage and type wheel to be as short as possible in order to increase the printing speed.